Technical Field
The present invention generally relates to detection and quantification of an analyte of interest. More specifically, the present invention relates to an apparatus and a method for detecting and quantifying biological and chemical analytes.
Description of the Related Art
Detection and quantification of various biological and chemical analytes has applications in a myriad of fields of use across many industries, including but not limited to, medical diagnostics, genomics and proteomics, food and beverage industry, national security and defence, and environmental monitoring.
Accordingly, reliable, time-efficient, and cost-effective identification and/or quantification of biological and chemical analytes are important fields of research across many industries.
In recent years, several sensing modalities for detection and/or quantification of biological and chemical analytes have been proposed.
One of the conventional techniques is based on fluorescence exhibited by many analytes of interest. According to this technique, visible markers are attached to analytes and also, a complex optical assembly including high intensity optical sources, optical filters and lenses, is then used to detect frequency range of emission, which serve to characterise an analyte of interest. Although such techniques provide good selectivity and sensitivity, the fluorescence-based sensing devices are inherently cumbersome, time-consuming, expensive, and accordingly, not suited for many applications such as point-of-care diagnostics.
In recent years, several methods based on antigen or genome detection have been proposed. One example of such methods is Enzyme Linked Immuno Sorbent Assay (ELISA) based protocols. However, such methods are virus specific and suffer from a limited dynamic range of detection. Other quantitative real-time methods such as polymerase chain reaction, flow cytometry, and techniques revealing viable cell size, have also been developed to aid determination of virus and other micro-organisms.
Another solution is the use of transmission electron microscopy (TEM) and different mass spectroscopy techniques. While these techniques are able to provide accurate and reliable information related to size and charge; they cannot characterize particles in their liquid environment and are expensive and time consuming. Moreover, these techniques require relatively high concentrations of the target analyte, which is impossible during the early diagnosis of many diseases.
A wide range of organic and inorganic materials typically found in biological and chemical analytes are known to be exhibit electrical properties. In the prior art, various techniques harnessing the electrical properties of such materials, in particular, the polarization response such materials to an external electric field have also been proposed.
Typical electrical-based detection and/or quantification modalities are designed to sense changes in electrical properties of an electrode surface functionalised using probes designed to bind to specific analytes of interest. Different types of electrochemical sensors such as charge transfer sensors, capacitance-based sensors, impedance-based sensors, and field-effect based sensors have been reported.
However, the currently available electrochemical sensors suffer from several disadvantages. The devices are expensive and restricted to detection of usually a single analyte. Several such devices are not conducive to reuse. These techniques invariably require extensive sample preparation such as sample staining using labels, biomarkers and so on. Moreover, the response time is undesirably high. In addition, such devices are usually bulky and not suitable for point-of-care applications.
In light of the foregoing, there is a need for reliable, time-efficient, and cost-effective identification and/or quantification of biological and chemical analytes.